Back support in a seated position is important to all persons, particularly those prone to back problems. Since traditional pillows are made with a fixed resilient structure, finding lower back support of desired firmness and thickness often entails locating and trying several different pillows or combinations before a suitable one is found. Bed support structures such as coil spring mattresses and water bed technology have not been found adaptable to pillows.
Ordinary pillows of known art are most commonly made resilient through the use of an appropriate stuffing material such as down, cellular foam or the like. As an alternative, running a distant second, air can be used for resilience in a sealed pillow bag, typically inflated by compressed air from an external source such as human breath, a motorized compressor or a hand operated pump, e.g. a bicycle tire pump. When the air pillow is inflated to a desired degree, the pressure source is removed and a valve seals the enclosure and prevents air escape as long as the enclosure remains air tight.
Unfortunately the air pillow is inherently subject to loss of air through leakage over time, and thus the more stable and reliable stuffed pillow has heavily predominated.
The air pillow does offer a significant advantage over the stuffed pillow in that it can be adjusted to a desired degree of effective thickness and support by controlling the amount of contained air. Once inflated to a working degree of support, the support is easily reduced by releasing air; however to increase the support again requires additional air input from one of the above-mentioned external pressurizing sources. This inherent inconvenience has greatly limited the use of air pillows as adjustable back support devices. Inflatable flotation devices for water sport and air mattresses for camping are popular because they can be deflated, folded and stored in a small space.
An example of a specialized institutional application that benefits from the adjustable feature of air inflation is found in hospital bed mattresses with multiple independently inflatable cells for preventing bedsores.
A further consideration in an adjustable back support pillow is the desirability of facilities for retaining thermo/therapeutic devices, e.g. cold packs for alleviating back pain.